Magnetic field sensors, such as Hall sensors, are sensitive to magnetic fields but can suffer from offset error. Offset error is the presence of an output signal in the absence of some input quantity. In an example related to Hall sensors, the offset error would be an output signal indicative of an input magnetic field when in fact no magnetic field is present. Offset error can affect both ordinary Hall devices and vertical Hall devices.
Offset error can relate to different causes, two of which are raw offset error and residual offset error. Raw offset error can refer to an offset error present in a particular operating phase. Residual offset error can refer to an offset error present in an overall or total output signal, such as a signal that is a combination of those from individual operating phases.
One approach for reducing or eliminating offset error is using a multi-terminal Hall sensor. Four-terminal Hall sensors can be operated in a spinning current-type mode, which changes the couplings of the terminals in each of multiple clock phases such that any offset is reduced when the signals from the multiple clock phases are combined. Three-terminal Hall devices typically require use of at least two devices and a modified spinning-current technique in order to be similarly operated. Even so, the residual offset error can remain higher than desired, such as in the range of about 1 milli-Tesla (mT).